Questions tagged [hvac]

(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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3answers
44 views

How to safely clean rust and prep on a section of HVAC ductwork before insulating

So I have a small section (about 1.5 ft) of non-insulated ductwork with some rust right above my HVAC blower/furnace in the basement. The rust seems to be caused by the water that sweats on that ...
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1answer
40 views

How to extract and then add new refrigerant oil to a home hvac system after existing oil was contaminated with humidity?

Condenser copper refrigerant lines were cut by vandals. They stayed open for several days. Before recharching with r-22, i know the repairmen will have to braze the copper lines and remove all the ...
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1answer
48 views

Furnace/HVAC issues in new build

Just had a couple of questions. I have been in new build townhouse for a month and noticed a couple of things but have been away several weeks so just dealing with it now. Some of this I am sure I am ...
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1answer
23 views

Furnace relay - old one says 18 LRA, replacement says 48 LRA - Does it matter?

forgive me if this is a newbie question. I am replacing a relay inside an electrical furnace/air handler. It is a relay model 90-293Q. The original one I have specifies it as "8 FLA, 18 LRA" but the ...
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2answers
72 views

Adding a return vent to a hot office

I have an office with a significant amount of computer equipment in it that generates quite a bit of heat and is regularly 3-12 degrees warmer than the rest of the house when I'm working in there with ...
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2answers
44 views

Heat pump not working after rain

A couple weeks ago, I had a Goodman 3 ton heat pump split system put in. At 5pm hours today, I was outside near the heat pump and noticed that it was functioning properly. At about 6pm, there was a ...
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1answer
26 views

Mold at Air Return

I have 2 HVAC units, one for upstairs and one for downstairs. When I went to change my air filter for the downstairs unit I noticed some mold in the return duct. This is a large duct that travels ...
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1answer
52 views

More wires than Nest needs

I had an old thermostat with wiring as below image: I wired Air Handler Trane (Model# TWE037E13FB2) in the attic just like it was before: Here is a wiring diagram of Air Handler: However, my Nest ...
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0answers
42 views

Replacing old thermostat and two unidentified wires

I'm replacing an old thermostat from the early 90's with a new wifi thermostat. When removing the old one, it only used R,G,Y,W wires, and the new wifi thermostat requires a C. After fully removing ...
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0answers
59 views

Why is my HVAC system not turning on the A/C compressor?

My AC stop cooling. Here's what I found. Inside blower is working, outside compressor/fan does not turn on. I manually push the contacts in the outside relay and the compressor and fan worked, used ...
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0answers
30 views

Only getting 15-16 volts from Furnace R and C

I recently purchased a smart thermostat. Because it needed a common wire and I only had a 3 wire setup, I ran a new thermostat wire to my furnace. However, I now get only 15 volts (inconsistently, ...
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0answers
30 views

New Unit with Blocked Condensate Lines

A little over 30 days ago a new HVAC unit was installed at my home. Saturday night I had a buckled ceiling and a BIG problem. The installer told me both primary and secondary lines were clogged—-the ...
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4answers
53 views

Should I switch to a vertical exhaust fan to avoid 90 degree bends?

I am replacing the original kitchen exhaust fan on my 1950s house. The old one vented sideways to an immediate 90-degree bend (to 8-inch rigid ducting) and then straight up about 24~36 inches to the ...
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2answers
26 views

combining a humidifier with refrigeration cooling, what do you think?

I live in a high humidity (75%) climate. I wanted to know what happens when you combine a light humidifier with a normal AC set on "dry" mode. The AC is activity reducing humidity, which helps me "...
3
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2answers
51 views

How to investigate a problem with blown 50 amp HVAC fuse without power?

My AC unit has the fan working but not the condenser and I found that one of the two 50 amp fuses was bad. Unfortunately after replacing it, I saw and heard a spark and the new fuse was blown ...
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2answers
51 views

Is it OK to stop the indoor blower during heat pump defrost on split-system heat pumps?

The traditional North American split system heat pump (ignoring "dual fuel" systems for now) relies on a backup heat source to provide both makeup heat during low-temperature (below the system balance ...
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1answer
43 views

Is my HVAC system one or two transformer based?

I have read Do I have one or two 24V transformers in HVAC control circuit, but as it appears I don't have two geographically separate units for A/C and heating, believe this to be a different question....
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2answers
138 views

Storing comsumable dry goods in your car in the summer? [closed]

I live in South Florida where the summer sun has no mercy. I drive a new van and I've taken steps to keep the inside cooler during the day. I live in the van for weeks at a time and need to store ...
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3answers
37 views

Fan is turning on air conditioner but no air movement

A few weeks ago I changed the outside unit's starting capacitor and that got the fan on that unit to rotate and the air conditioning on the enclosed back porch started working. Today I came home and ...
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4answers
58 views

What parameters affect the amount of btu required to cool a single room

Background Due to the reason I lack knowledge in air conditioning I asked a company that manufactures and sells a\cs to send a consultant to advise me on which air conditioner I should use in my room....
23
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7answers
10k views

Why does my house heat up, even when it's cool outside?

Summary The question pretty much says it all. It's probably a ridiculously easy one to answer. It's cool outside but I know that my house is heating up because my AC kicks on periodically. I've ...
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1answer
1k views

What causes burn marks on the air handler in the attic?

What caused these burn marks? Phoenix Arizona suburb. House was construction complete about 6 months ago. The tape and insulating foam around the bigger tube was cut. I assume the AC tech that ...
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2answers
33 views

Thermostat “fan” function actually using air conditioning

A few months ago, my wife and I started sleeping with our bedroom doors closed to keep out our cat. We would wake up in the middle of the night to find our bedroom was very hot and it felt really hard ...
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3answers
61 views

I need to pressurize a room and I'm kind of at a loss as to how to do it, hoping someone out there might have some advice

I'm setting up a small packaging operation for edible products for pets. There are certain government standards we have to hit to be able to do this. The actual packaging takes place in a 420 sq ft ...
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1answer
27 views

Mini Split Condenser wall mount on wood exterior wall

We have a wood-frame house with 2x4 studs and half-inch plywood exterior walls. What is the generally accepted best practices for mounting a 80lb mini split condenser on a wall bracket to this type of ...
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1answer
60 views

Can I draw 240v out of this configuration?

This is how my subpanel looks like. I am looking to install a breaker for an AC unit. 20A. The only caveat is that this has to be 240V. This is a subpanel coming from the main one. There is a breaker ...
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2answers
38 views

Adjusting HVAC damper

First summer in this 2 story house and looks like air flow on the second floor is significantly weaker then on the bottom floor. Looked at the HVAC to find the dampener handle and found 1 but it is ...
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1answer
30 views

Add common wire to furnace

Trying to add common wire to furnace for smart thermostat. Looking at wiring diagram, it looks like common wire off transformer is blue, switches wire color to white (via wire cap), then back to blue (...
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1answer
63 views

What is the fully burdened hourly rate for an HVAC installer? [closed]

While it's pretty simple to get an hourly rate that is paid to an HVAC installer, I have found it more difficult to ascertain what the fully burdened rate is. This is the complete cost a company to ...
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3answers
63 views

Water/antifreeze radiator cooled work shop

An additional line of thought. Cooling radiators in summer? I found this having the same concept for cooling. I live in south louisiana, US where 95F is vary common turning tin boxes into a slow ...
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0answers
21 views

HVAC plastic drainage tube snapped off outside

The plastic tube where the condensate drains outside has broken off partly. I would say about 2/3 of it broke off. It still points away from the house a little so shouldn’t get on the wall. Should I ...
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2answers
66 views

condenser capacitor question

My outside condenser fan quit running, so I tested the capacitor, and got nothing on the meter. The cap that was in there was a 35/7.5. The closest one I could find at the time was a 50/7.5. Now ...
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0answers
18 views

Hvac fuse blowing on furnace board

A 5 amp fuse keeps popping at startup on my tempstar furnace,had a problem a couple weeks ago and put fuse in and worked fine.Now it blows instantly.
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1answer
42 views

Adding ventilation to an older outbuilding

I have a large to me storage building that I am trying to convert into a garage/workshop. I don't have the time/money/inclination to tear the whole thing down and start anew so I am trying to make ...
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2answers
26 views

Placement of a package unit heat pump for my shop

I was wondering if I would benefit by locating my 3 ton package unit heat pump closer to the load center. The ducting would be my only interference with it closer to the load center. The unit would ...
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1answer
53 views

Return plenum too big for air handler?

I am currently in the process of changing the air handler and heat pump in my house. I am working with a friend's father who does HVAC for a living. He came over and looked at my HVAC system and gave ...
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0answers
42 views

Split unit Air Conditioner replace compressor single to three phase

I have a 3-ton split AC "single-phase compressor" was working perfectly until I moved it to another location, some oil spilled from the suction pipe during the transportation so when I installed it in ...
5
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1answer
62 views

How do motor capacitors change in value with respect to age or environmental factors?

Do motor capacitors (i.e. start, run capacitors) change in value with respect to age or other environmental factors? I understand they fail, as observed when the motor will no longer start. Do they ...
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1answer
20 views

Fan on propane furnace not coming on

I have a Honeywell model number NHGK076AF01 propane furnace. It is about 15 years old. The problem started when I noticed the breaker had tripped and I had no heat. After resetting breaker, I tried ...
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2answers
45 views

Musty Smell in slab and block house

As my title states, I have a house that is on a slab and the exterior and most interior walls are block and covered with plaster. Since we bought the house we have noticed a musty smell that we ...
26
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2answers
3k views

What is an air conditioner compressor hard start kit and how does it work?

My air conditioner compressor wasn't functioning properly recently. The compressor wouldn't start when the start relay energized. A HVAC technician diagnosed the problem nebulously as "It needs a hard ...
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1answer
36 views

AC unit dripping onto crawl space vapor barrier

I just bought a house whose crawlspace looks like it was partially converted to being sealed off. Basically, they put down a vapor barrier and closed off the vents, but didn't finish the job. On top ...
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1answer
46 views

Window AC fan drip pan full

My AC started to blow out pretty lukewarm air recently, as well as make watery sounds while running. I realized the filter was dirty, and I cleaned the coils, replaced the filter and removed lots of ...
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1answer
53 views

How do I remove these ceiling diffuser flaps?

I need to move this diffuser away from the wall and can't figure out how to take out the flaps that are installed. They don't have any screws on the inside that I can see. Is there a trick to ...
0
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1answer
34 views

How thoroughly should HVAC evaporator be sealed?

I noticed that cold air was rushing out of the seam near my AC evaporator, so I added foil tape around the seam (see photo). Is that appropriate, or does that minor leakage serve a purpose? The rest ...
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1answer
40 views

Is the PY4G HVAC unit compatible with Nest Thermostat?

I recently bought a Nest Thermostat and I've had nothing but trouble with it. The main symptom is the fan and the AC compressor won't run at the same time. Power only comes through the green wire, not ...
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1answer
17 views

AC red wire placement on control board?

So a fuse(3) on my control board blew at the same time my ac capacitor did. I replaced the capacitor with the exact one that was on the old unit and when replacing the fuse noticed a stray red wire... ...
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0answers
29 views

Using existing hot water vent for extraction

I have a room in the basement with equipment (computers) that gets really hot. There is an ac vent but the thermostat is nowhere near the room. Also in an alcove is the hot water heater behind a ...
3
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2answers
230 views

AC contactor 1 pole or 2?

I wanted to title this: Outside unit running, but thermostat is off but I'm 99% sure its the contactor unless someone here says otherwise. Thus my real question: which contactor should I buy? I typed ...
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1answer
15 views

Adapter for NTC boiler probe

I just bought a replacement NTC probe for my boiler (bought with specific part number) but once the item arrived I noticed the connector wasn't matching. I think this is due to past maintenance when ...